296 



EFFECT OF CHEMICAL AGENTS 



[Cn. XI 



PLANTS 



a. Analysis of the Entire Organism. We are now ready to 

 consider the atomic composition of the dry substance of organ- 

 isms. VOLKMANN ('74) has contributed data on this subject 

 in the case of man. Thus the dry substance gives : 



c 

 52.9% 



o 

 18.5% 



H 



7.7% 



N 



7.4% 



ASH 



13.4% 



In the case of a plant (stems and leaves of dry clover) we 

 have, according to JOHNSON : 



C 



47.4% 



O 



37.8% 



H 



5.0% 



2.1% 0.12% 



P KEMAININO ASH 



0.30% 2.0% 



These two determinations, fairly typical of the higher plants 

 and the higher animals respectively, run nearly parallel. The 

 greatest difference is shown by the nitrogen, which is more than 

 three times as abundant in animals as in plants. Oxygen, on 

 the other hand, is more abundant in plants. 



The ash, in turn, must be further analyzed. The following 

 table gives the percentage composition of the ash of various 

 organisms : 



TABLE XXVI 



